| 摘要 |
PURPOSE:To prevent the adhesion of quartz rich in silicon, and to obviate the generation of a foreign matter while checking the large reduction of the rate of film formation by mixing 0.5% or less of oxygen into argon gas. CONSTITUTION:When the quantity of oxygen mixed into argon gas is altered at approximately 0.1%, characteristics as shown in the graph are acquired. That is, when the quantity of oxygen is increased, the difficulty of the peeling of extraneous quartz is augmented and the generation of foreign matters is inhibited, but the rate of film formation is decreased: when the quantity of oxygen is reduced, the rate of film formation is accelerated, but the difficulty of the peeling of extraneous quartz is lowered and foreign matters are easy to be generated. Consequently, the quantity of oxygen mixed into argon gas is set so as to be brought to 0.5% or less at most centering around 0.1%. Accordingly, both points of the rate of film formation and the difficulty of the peeling of extraneous quartz can each be satisfied.
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